Nearly diffraction-limited picosecond pulse amplification from LMA fluoride fiber at 2.8 µm

Area of Science:

• Laser Physics
• Optical Engineering
• Materials Science

Background:

• Fiber amplifiers are crucial for generating high-energy laser pulses.
• Achieving high beam quality from large-mode-area fibers is challenging.
• Mid-infrared wavelengths (2.8 µm) are important for specific applications like biomaterial processing.

Purpose of the Study:

• To demonstrate the generation of a nearly diffraction-limited picosecond pulse from a large-mode-area (LMA) fluoride fiber amplifier.
• To characterize the performance of the LMA Er:ZBLAN fiber amplifier at 2.8 µm.
• To assess the potential of this system for high-precision biomaterial processing.

Main Methods:

• Seeding a mode-locked fiber oscillator at 2.8 µm.
• Utilizing a 50 µm LMA Er:ZBLAN fiber amplifier.
• Employing the fundamental mode excitation technique.
• Measuring beam quality using M² values.

Main Results:

• Generation of a 16 µJ picosecond pulse with a 70 ps duration at 5 kHz repetition rate.
• Achieved nearly diffraction-limited beam quality with M² values of 1.25 (x-axis) and 1.27 (y-axis).
• Demonstrated successful operation of the LMA fiber amplifier at 2.8 µm.

Conclusions:

• The developed LMA Er:ZBLAN fiber amplifier system successfully generates high-energy, nearly diffraction-limited picosecond pulses at 2.8 µm.
• The system's high beam quality and energy output indicate significant potential for high-precision biomaterial processing.
• This work advances the capabilities of fiber-based laser systems in the mid-infrared spectrum.